Beds are sanctuaries, the place where we begin and end each day. But for some British men, keeping that sanctuary tidy by changing the bed sheets on a regular basis apparently falls low on their priority list. A new survey by U.K. mattress company Ergoflex reveals that young, single British men are the worst offenders, changing sheets a mere once every three months.

Single women reported swapping linens every two and a half weeks, while couples claimed to change sheets every two weeks. Of those couples, the study found 81% of those washing the sheets were women. Of the 2,004 interviewed, on average men admitted to owning only one set of sheets while women estimated around three selections.

Though it’s clear that females are cleaner overall, the results found that age is a factor as well. For those who answered once every three months, 55% were ages 18 to 25 with men accounting for 71%, while those who claimed to wash sheets once a week were in the 35 to 50 age range. Of the weekly washers, 62% were female. Indeed, 17% of single men participating in the study admitted that partners found their unhygienic practices unnerving compared to just 2% of women.

“We were quite alarmed at the apparent lack of basic hygiene from some respondents,” said Jed MacEwan, a spokesman for Ergoflex, as reported by the Daily Mail. Experts like Philip M. Tierno Jr., director of clinical microbiology and immunology at New York University’s Langone Medical Center recommend washing bed linens and pillowcases once a week to prevent respiratory problems and reduce debris like dead skin, dander, body secretions and bacteria that accumulate while we sleep.

“One person can perspire as much as a liter in a night—even more if you have a lot of covers,” he told the Wall Street Journal. Tierno also explained that skin cells are a source of food for mites, who are known to fester in mattresses and bedding, and also leave their feces behind. Fungal mold, fungal spores, lint, fibers, pollen, soil and cosmetics also accumulate in the often harmless looking sheets.